1. Field of the Invention
The present invention relates to a new process for the preparation of 9,10-dihydro-9-oxa-10-organylphospha-phenanthrene-10-oxide and its derivatives substituted on the phenyl groups. The invention also relates to a process for the preparation of natural products and plastics with flame-retardant finishing using these derivatives.
2. The Prior Art
A process is known from the state of the art for the preparation of 9,10-dihydro-9-oxa-10-alkoxyphospha-phenanthrene-10-oxide and substituted derivatives of same by alcoholysis of 9,10-dihydro-9-oxa-10-halophosphaphenanthrene-10-oxide and its substituted derivatives in the presence of stoichiometric quantities of bases, such as tertiary amines or ammonia. See e.g. EP-A-0 787 738, EP-A-0 304 782 and also Phosphorus and Sulfur 1987, 31, page 71.
As alternative educts, but only for the preparation of 9,10-dihydro-9-oxa-10-aryloxyphosphaphenanthrene-10 derivatives, triphenyl phosphites or combinations of triphenyl phosphite/PCl3 are disclosed in DE-A-20 34 887 or U.S. Pat. No. 3,702,878. These processes are however associated with the use of very high reaction temperatures of roughly 200° C. Furthermore transesterification reactions which can start from the said aryloxy derivatives are possible only with long-chained, low-volatility alcohols. 9,10-dihydro-9-oxa-10-organylphosphaphenanthrene-10-oxide derivatives can be obtained from the 9,10-dihydro-9-oxa-10-aryloxyphospha-phenanthrene derivatives by further reaction with stoichiometric quantities of organyl halides, preferably bromides and iodides, or in the case of phosphites also with stoichiometric quantities of alkylation agents that contain no halides. This therefore involves an application of the standard Michaelis-Arbuzov reaction (see Chem. Rev. 1981, 81, pages 415-430).
It is disclosed in Macromol. Rapid. Comm. 2001, 22, 1265-71 that 9-(9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide)-1-propene can be obtained by reacting 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOP) with methylene chloride and allyl bromide. The corresponding reaction with epichlorohydrin instead of allyl bromide, whereby 9-(9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide)-2-propene-1-ol can be obtained, is also disclosed.
Organic phosphorus compounds in which optionally substituted 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide units are connected by bivalent hydrocarbon radicals which optionally contain heteroatoms or functional groups are known as flame-protection additives from JP-A-2001270993. Reference is made to JP-A-63135396 and 11106619 as regards the preparation of these phosphorus compounds. The abstract of JP-A-11106619 discloses that during preparation halogen-containing compounds such as 1,2-dichloroethane are used. The abstract of JP-A-63135396 discloses that the preparation takes place starting from a phosphinic acid derivative, which has an aromatic diol group, which is reacted with a glycidyl compound such as polyethylene glycol diglycidyl ether in solvent, preferably in the presence of a catalyst, e.g. Li, Mg, Cu or Fe, accompanied by heating.
Similar bridged phosphorus compounds as those disclosed in JP-A-2001270993 are disclosed in JP-A-57105456 and 57105451.
The abovementioned preparation of the 9,10-dihydro-9-oxa-10-alkyl-oxyphosphaphenanthrene derivatives by alcoholysis of the 9,10-dihydro-9-oxa-10-halophospha-phenanthrene derivatives (halogen e.g. chlorine) using bases (EP-A-0 787 738) requires a two-step prior preparation of the 10-halogen derivative with an unsatisfactory overall yield of less than 50%.
Preparation starting from the relatively expensive educt triphenyl phosphite or triphenyl phosphite/PCl3 is also characterized by disadvantageous reaction conditions and a limited accessible product range, namely aromatic substituents only. In order to arrive at the desired end-products, such as 9,10-dihydro-9-oxa-10-organylphospha-phenanthrene-10-oxide and its substituted derivatives, further reaction steps must be carried out in each case using stoichiometric quantities of further reactants (transesterification, stoichiometric Michaelis-Arbuzov reaction). There are therefore in each case several (at least two to four) separate chemical reactions to be carried out, each accompanied by costly purification and separation operations.
A further disadvantage of the processes of the state of the art is that halogen-containing reactants must be used in stoichiometric quantities. Examples of this are the above-mentioned standard Michaelis-Arbuzov reaction or the stoichiometric reaction with allyl bromide as described in Macromol. Rapid. Comm. 2001, 22, 1265-71.
On the other hand 9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide (DOP) is commercially available on an industrial scale and can be prepared in yields of over 95% in a one-step synthesis, see e.g. EP-A-0 806 429.
EP-A-1 279 719 describes flame-retardant fiber-treatment agents based on DOP derivatives. Alkyl, hydroxyalkyl, aralkyl, succinimide, hydroxy, alkoxy or aralkoxy groups are provided as substituents on the phosphorus. In U.S. Pat. No. 4,228,064 and U.S. Pat. No. 4,198,492 similar compounds are proposed for the preparation of polyphenyleneether resin compositions with flame-retardant finish.